This invention relates to the identification of unknown bacteria by means of simultaneously performed biochemical reactions. More particularly it relates to a unique method for transforming the results of the biochemical reactions into a numerical profile representative of the bacterium being tested and subsequently consulting a Profile Register to obtain the identification.
A mechanical coder is provided which enables the user to efficiently transform the above-stated results to the numerical profile. This mechanical coder may also be provided with a color check feature to enable the user to visually verify his results.
The identification of bacteria is based on several characteristics of these organisms: reaction to certain biochemicals, serological behavior, lysotyping, bacteriophage, morphology, physiology, cell arrangement, etc.
In the routine clinical laboratory, the biochemical reactions form the primary basis for classification at the level of the tribe and the genus within the family Enterobacteriaceae. The behavior of bacterial organisms with particular biochemicals has been reported by several investigators. See, e.g., Edwards, P. R. and Ewing, W. H. Identification of Enterobacteriaceae. Third edition. Burgess Publishing Company, Minneapolis, Minnesota., 1972; Le Minor, L. Le diagnostic de laboratoire des bacilles a gram negatifs Enterobacteries. Tome 1, 4.sup.e edition, 1972. Editions de la Tourelle, St. Mande - 94, France; Cowan, S. T. and Steel, K. J. Manual for the Identification of medical bacteria. Cambridge at the University Press, 1970; Kauffman, F. The bacteriology of Enterobacteriaceae. Second edition, 1969. The Williams & Wilkins Company, Baltimore, Maryland.
Some of these reactions are clear-cut, being mostly positive or negative, whereas some others are variable. Based on a large number of organisms, percentages of positive or negative reactions have been established and reported. Several schema to interpret the results of biochemical reactions have been developed.
Because of the complexity of the interpretation of the data obtained, a sequential method of dichotomous keys, presented in the form of flow diagrams, is presently widely used. These flow diagrams base the selection of each succeeding biochemical test on the results of the previous one. This approach, even though practical in routine, is a simplification which, in the case of less common biotypes, can lead to misidentification.
The possible application of computer technology in the clinical laboratory has allowed a new approach toward the identification of an organism in testing it simultaneously with a large number of biochemicals. The computer memory can store probability of occurrence for each biochemical and, when matched with an unknown, the computer can provide a diagnosis based on probability. Minimum level of probability can establish the acceptability of the answer provided. This approach requires a huge memory which imposes the use of a computer and has the setback of describing combinations of reactions which are mathematically possible, but never encountered in organisms.
The Profile Recognition Method of this invention also tests the organisms simultaneously with a large number of biochemical characters, but only describes combinations which are most probably to occur with actual organisms. For example, for twenty biochemical reactions, the computer would allow 1,048,576 combinations. On the other hand traditional flow diagram techniques would only provide less than one hundred combinations. The Profile Recognition Method of the invention provides about 1500 combinations which is a more realistic number of combinations considering the probable number of biotypes.
The method of this invention enables the user to convert the results of the biochemical tests into a Profile Recognition Number, which is utilized to identify the bacterium by consulting a Profile Register. Methods are provided in the Profile Register to account for rare strains of bacteria as well as to aid in correcting errors in interpreting the biochemical test results made by the user.
The identification process can be further simplified by use of a coder to generate the Profile Recognition Number. This enhances the speed of identification.
Errors in transforming the biochemical test results into the Profile Recognition Number may be made by the user. To reduce these errors, the coder may also be provided with a colorcheck feature, whereby the user can visually compare the colors produced in the reaction chambers with a set of colors generated on the coder corresponding to the indicated Profile Recognition Number.
As used herein, the terms "numerical profile," "Profile Recognition Number," "number" and "didit" are understood to include both numerical and alphanumerical representations.